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(No Model.) 2 SheetsSheet 1. F. M. CAMPBELL.

HOT AIR FURNACE. No. 414,018. Patented 001;. 29, 1889.

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(No Model.) 2 Sheets-Sheet 2. F. M. CAMPBELL.

HOT AIR FURNACE.

No. 414,018. Patented Oct. 29, 1889'.

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UNITED STATES PATENT OFFICE.

FRANCIS M. CAMPBELL, OF ST. LOUIS, MISSOURI, ASSIGNOR OF ONE-HALF TO XVILLIAM THUENER, OF SAME PLACE.

HOT-AIR FURNACE.

SPECIFICATION forming part of Letters Patent No. 414,018, dated October 29, 1889.

(No model.)

To all whom it may concern.-

Be it known that I, FRANCIS M. CAMPBELL, of St. Louis, Missouri, have made a new and useful Improvement in Hot-Air Furnaces, of

which the following is a full, clear, and exact description.

The improvement relates especially to the system of fines traversed by the products of combustion in their escape from the combus- IO tion-chamber, substantially as is hereinafter described and claimed, reference being had to the annexed drawings, making part of this specification, in which- Figure 1 is a rear elevation of the improved furnace, portions of the furnace-wall and fines being broken away to exhibit the interior construction; Fig. 2, a horizontal section on the line 2 2 of Fig. 1, and Fig. 3 a horizontal section on the line 3 3 of Fig. 1.

The same letters of reference denote the same parts.

A represents the combustion-chamber o the furnace. It is of the customary form, saving as it maybe modified or supplemented by the improvement under consideration. Its door appears at a, Fig. 2, and its grate at a. The chamber A is substantially an upright one, and leading from its upper portion are two escape-fines B B, Figs. 1 and 2. The fines respectively lead into two upright fines O C, at or toward the upper portion thereof. The fines O C at the lower end thereof connect with a horizontal chamber D and respectively toward the ends (Z cl thereof. The exit from the chamber D is by means of an upright flue E, Figs. 1 and 2, which rises from the chamber D, midway between the fines O O, and at its upper end connects with any suitable escape-flue. (Not shown.)

0 F represents the customary furnace wall or case for inclosing the hot-air chamber G, Figs. 1, 2, and 3. The cold-air inlet to the chamber Gis at H, Figs. 1, 2, and 3, at the back part of the chamber G, as shown, and the chamber D is also at the back part of the chamber G, and it is arranged above the level of the inlet H, and the chamber D, as shown substantially in Figs. 2 and 3, is at its rear portion extended forward to come near the case F, and laterally is extended to come well to the sides of the combustion-chamber A, by which means a narrow space 9 is provided immediately above the inlet H, at the back of the combustion-chamber and in the rear of the chamber D and fines O O E, and a much larger space g at each side of the combustion-chamber for the air as it becomes heated to rise in. By reason of this a larger portion of the air is directed toward the central portion of the chamber G, and thus to the best advantage so far as heating it is concerned.

The operation is as follows: The heated products of combustion escape from the chamber A into the descending fines O C, which are quite large in diameter, and larger than the flue E. Owing to their size and to the use of a pair of them the fines C C are suflicient for the chamber A and no direct escape is needed. The course from the fines C O is downward into the chamber D, which serves not only to provide an additional heating-surface, but also as a dust-chamber and as a guard to favor the delivery-of the incoming cold air toward the central portion of the chamber G. From the chamber D the escape is, as stated, upward through the flue E.

It will be observed that the horizontal chamber D is not connected with the chamber A, but is separated therefrom, thereby providing additional heating-surface, and space g between the chambers A and D for the air to rise in. The chamber D is provided at its lateral extension with horizontal air-ports d d, which extend through the wall of the hot-air chamber and by drawing in air increase, the draft up the flue E. When desired, these parts may be closed. The combustion-chamber A is situated eccentrically within the hot-air chamber G, and the chamber D, to produce heat within the hot-air 9o chamber, is situated at the side of the latter opposite that containing the combustionchamber, and is moreover directly and centrally above the air-inlet H, so that said chamber heats the air as it is entering and heats it at the farthest possible point from the combustionchamber. The descending flues C C are of much larger diameter than the ascending fine E. This is for the purpose of retarding the descent through the I00 flues C C and increasing the radiating-surface thereof, so that by means of said retarding and increased surface the greatest possible amount of heat will be thrown out from the descending fiues into the air-chamber. As the ascending fine E is much smaller in diameter than the descending fines O O, the air Will of course pass much more rapidly upward therethrough than it can descend in the fines O O.

I claim- 1. In a furnace, the combination, with the hotair chamber having an air-inlet in one side near its bottom, of the combustionchamber situated eccentrically within the hot-air chamber and adjacent to the side thereof opposite that having the air-inlet, the dues B B, extending from the inner side of the combustion-chamber near the top thereof the descendin fines C C commu- 7 b 7 nicating at top with the fines B B, respectively, the chamber D, communicating With the lower ends of the flues O C, and the ascending flue E, rising centrally from the chamber between the flues B B, substantially as specified.

2. The combination, With the hot-air chamber having the air-inlet in one side near its bottom, of the combustion-chamber situated eccentrically Within the hot-air chamber near the side opposite that having the air-inlet, the chamber D, immediately above the airinlet, and provided With the air-ports d d at its lateral extensions, the fines B C and B C, respectively connecting the said lateral extensions with the upper portion of the combustion-chamber, and the ascending flue rising from the chamber D midway between the flues O O, substantially as specified.

3. In a furnace, the combination, with the hot-air chamber and the combustion-chamber situated eccentrically therein, of the fiues B B, extending from the top of the combustionchamber, the descending flues O C, of large diameter, communicating, respectively, with the fiues B B, the heating-chamber D, communicating with the lower ends of the lines O O', and the ascending flue E, rising from the chamber D between the fines O O and of much smaller diameter than the latter fiues, as and for the purposes set forth.

Witness my hand this 21st day of February, 1889.

FRANCIS M. CAMPBELL.

Witnesses:

O. D. MooDY, D. WV. A. SANFORD. 1 

